Since plasma displays (PDPs) allow high speed displaying and can be enlarged compared to liquid crystal panels, they are widely in such areas as OA apparatuses and information displays. As they are increasingly used in more areas, color PDPs having many fine display cells attract special attention.
In a PDP, plasma discharges are caused between anodes and cathodes located to face each other in discharge spaces formed between a front glass board and a rear glass board, to let the gas hermetically contained in the spaces emit light, for displaying.
A PDP is formed by bonding together a front glass board and a rear glass board respectively having electrodes, dielectric layer, etc. The rear glass board usually has a plurality of striped barrier ribs formed and in the cells formed between the respectively adjacent barrier ribs, phosphor layer stripes are formed for color displaying in red, green and blue. These phosphor layer stripes are formed by coating the respective cells with an R (red) light emitting phosphor, G (green) light emitting phosphor or B (blue) light emitting phosphor usually by screen printing, and drying and firing the respective phosphors. To achieve a higher luminance, it is also practiced to form the phosphor layer stripes not only on the bottoms but also on the lateral faces of the cells, for forming a phosphorescent face (U.S. Pat. No. 5,674,553).
As described above, the cells for displaying R, G and B are formed between striped barrier ribs, and the barrier ribs are formed at a constant pitch. Therefore, the respective phosphor layer stripes of R, G and B are equally sized.
Presently developed red light emitting phosphors include Y2O3:Eu, YVO4:Eu, (Y, Gd)BO3:Eu, Y2O3S:Eu, g-Zn3(PO4)2:Mn, (ZnCd)S:Ag+In2O3, etc.
Green light emitting phosphors include Zn2GeO2:Mn, BaAl12O19:Mn, Zn2SiO4, LaPO4:Tb, ZnS:Cu, Al, ZnS:Au, Cu, Al, (ZnCd)S:Cu, Al, Zn2SiO4:Mn, As, Y3Al5O12:Ce, CeMgAl11O19:Tb, Gd2O2S:Tb, Y3Al5O12:Tb, ZnO:Zn, etc.
Blue light emitting phosphors include Sr5(PO4)3Cl:Eu, BaMgAl14O23:Eu, BaMgAl16O27:Eu, BaMg2Al14O24:Eu, ZnS:Ag+red pigment, Y2SiO3:Ce, etc.
As light emission characteristics of these light emitting phosphors, important are the luminance, emitted color and afterglow, but there is few perfect phosphors. Especially the luminances of blue light emitting phosphors are lower than those of red and green light emitting phosphors, and in the case of color display, a well-balanced color image is unlikely to be obtained disadvantageously. At present, a color display is designed in reference to the level of the blue light emitting phosphor.